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x509(1ssl)
NAME
x509 - Certificate display and signing utility
SYNOPSIS
openssl x509 [-inform DER | PEM | NET] [-outform DER | PEM | NET] [-keyform
DER| PEM] [-CAform DER | PEM] [-CAkeyform DER | PEM] [-infilename]
[-outfilename] [-serial] [-hash] [-subject] [-issuer] [-nameopt option]
[-email] [-startdate] [-enddate] [-purpose] [-dates] [-modulus]
[-fingerprint] [-alias] [-noout] [-trustout] [-clrtrust] [-clrreject]
[-addtrust arg] [-addreject arg] [-setalias arg] [-days arg] [-signkey
filename] [-x509toreq] [-req] [-CA filename] [-CAkey filename]
[-CAcreateserial] [-CAserial filename] [-text] [-C] [-md2 | -md5 | -sha1 |
-mdc2] [-clrext] [-extfile filename] [-extensions section]
INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
-inform DER|PEM|NET
Specifies the input format. Normally the command will expect an
X509 certificate but this can change if other options such as -req
are present. The DER format is the DER encoding of the certificate,
and PEM is the base64 encoding of the DER encoding with header and
footer lines added. The NET option is an obscure Netscape server
format that is obsolete.
-outform DER|PEM|NET
Specifies the output format. The options have the same meaning as
the -inform option.
-in filename
Specifies the input filename to read a certificate from or standard
input if this option is not specified.
-out filename
Specifies the output filename to write to or standard output by
default.
-md2|-md5|-sha1
The digest to use. This affects any signing or display option that
uses a message digest, such as the -fingerprint, -signkey and -CA
options. If not specified then MD5 is used. If the key being used
to sign with is a DSA key then this option has no effect. SHA1 is
always used with DSA keys.
DISPLAY OPTIONS
-text Prints out the certificate in text form. Full details are output
including the public key, signature algorithms, issuer and subject
names, serial number any extensions present and any trust settings.
-noout Prevents output of the encoded version of the request.
-modulus
Prints out the value of the modulus of the public key contained in
the certificate.
-serial Outputs the certificate serial number.
-hash Outputs the hash of the certificate subject name. This is used in
OpenSSL to form an index to allow certificates in a directory to be
looked up by subject name.
-subject
Outputs the subject name.
-issuer Outputs the issuer name.
-nameopt option
Option which determines how the subject or issuer names are
displayed. This option may be used more than once to set multiple
options. See the Name Options section for more information.
-email Outputs the email address if any.
-startdate
Prints the start date of the certificate, that is the notBefore
date.
-enddate
Prints the expiration date of the certificate, that is the notAfter
date.
-dates Prints the start and expiration dates of a certificate.
-fingerprint
Prints the digest of the DER encoded version of the whole
certificate.
-C Outputs the certificate in the form of a C source file.
The -alias and -purpose options are display options but are described in
the Trust Options section.
TRUST OPTIONS
These options are experimental and may change.
A trusted certificate is an ordinary certificate which has several
additional pieces of information attached to it, such as the permitted and
prohibited uses of the certificate and an alias.
Usually when a certificate is being verified, at least one certificate must
be trusted. By default a trusted certificate must be stored locally and
must be a root CA. Any certificate chain ending in this CA is then usable
for any purpose.
Trust settings are only used with a root CA. They allow finer control over
the purposes of the root CA. For example, a CA may be trusted for SSL
client but not SSL server use.
See the description of the verify utility for more information on the
meaning of trust settings.
Future versions of OpenSSL will recognize trust settings on any
certificate, not just root CAs.
-trustout
Causes x509 to output a trusted certificate. An ordinary or trusted
certificate can be input, but by default an ordinary certificate is
output and any trust settings are discarded. With the -trustout
option a trusted certificate is output. A trusted certificate is
automatically output if any trust settings are modified.
-setalias arg
Sets the alias of the certificate. This will allow the certificate
to be referred to using a nickname, such as Steve's Certificate.
-alias Outputs the certificate alias, if any.
-clrtrust
Clears all the permitted or trusted uses of the certificate.
-clrreject
Clears all the prohibited or rejected uses of the certificate.
-addtrust arg
Adds a trusted certificate use. Any object name can be used here
but only clientAuth (SSL client use), serverAuth (SSL server use)
and emailProtection (S/MIME email) are used. Other OpenSSL
applications may define additional uses.
-addreject arg
Adds a prohibited use. It accepts the same values as the -addtrust
option.
-purpose
Performs tests on the certificate extensions and outputs the
results.
Certificate Extensions
The -purpose option checks the certificate extensions and determines what
the certificate can be used for. The actual checks are complex and include
various hacks and workarounds to handle broken certificates and software.
The same code is used when verifying untrusted certificates in chains.
The basicConstraints extension CA flag is used to determine whether the
certificate can be used as a CA. If the CA flag is true then it is a CA.
If the CA flag is false then it is not a CA. All CAs should have the CA
flag set to true.
If the basicConstraints extension is absent then the certificate is
considered to be a possible CA. Other extensions are checked according to
the intended use of the certificate. A warning is given in this case
because the certificate should not be regarded as a CA. However, it is
allowed to be a CA to work around some broken software.
If the certificate is a V1 certificate (and thus has no extensions) and it
is self signed it is also assumed to be a CA, but a warning is given. This
is to work around the problem of Verisign roots which are V1 self signed
certificates.
If the keyUsage extension is present then additional restraints are made on
the uses of the certificate. A CA certificate must have the keyCertSign bit
set if the keyUsage extension is present.
The extended key usage extension places additional restrictions on the
certificate uses. If this extension is present (whether critical or not)
the key can only be used for the purposes specified.
The comments about basicConstraints and keyUsage and V1 certificates apply
to all CA certificates. A complete description of each test follows:
· SSL Client
The extended key usage extension must be absent or include the web
client authentication OID. The keyUsage extension must be absent or
it must have the digitalSignature bit set. Netscape certificate type
must be absent or it must have the SSL client bit set.
· SSL Client CA
The extended key usage extension must be absent or include the web
client authentication OID. Netscape certificate type must be absent or
it must have the SSL CA bit set. This is used as a work around if the
basicConstraints extension is absent.
· SSL Server
The extended key usage extension must be absent or include the web
server authentication and/or one of the SGC OIDs. The keyUsage
extension must be absent or it must have the digitalSignature, the
keyEncipherment set or both bits set. Netscape certificate type must
be absent or have the SSL server bit set.
· SSL Server CA
The extended key usage extension must be absent or include the web
server authentication and/or one of the SGC OIDs. Netscape
certificate type must be absent or the SSL CA bit must be set. This is
used as a work around if the basicConstraints extension is absent.
· Netscape SSL Server
For Netscape SSL clients to connect to an SSL server it must have the
keyEncipherment bit set if the keyUsage extension is present. This
isn't always valid because some cipher suites use the key for digital
signing. Otherwise it is the same as a normal SSL server.
· Common S/MIME Client Tests
The extended key usage extension must be absent or include the email
protection OID. Netscape certificate type must be absent or should
have the S/MIME bit set. If the S/MIME bit is not set in netscape
certificate type then the SSL client bit is tolerated as an
alternative but a warning is shown. This is because some Verisign
certificates don't set the S/MIME bit.
· S/MIME Signing
In addition to the common S/MIME client tests the digitalSignature bit
must be set if the keyUsage extension is present.
· S/MIME Encryption
In addition to the common S/MIME tests the keyEncipherment bit must be
set if the keyUsage extension is present.
· S/MIME CA
The extended key usage extension must be absent or include the email
protection OID. Netscape certificate type must be absent or must have
the S/MIME CA bit set. This is used as a work around if the
basicConstraints extension is absent.
· CRL Signing
The keyUsage extension must be absent or it must have the CRL signing
bit set.
· CRL Signing CA
The normal CA tests apply, except in this case the basicConstraints
extension must be present.
SIGNING OPTIONS
The x509 command can be used to sign certificates and requests. It can thus
behave like a mini CA.
-signkey filename
Causes the input file to be self-signed using the supplied private
key. If the input file is a certificate it sets the issuer name to
the subject name (i.e. It makes it self-signed, changes the public
key to the supplied value, and changes the start and end dates.)
The start date is set to the current time and the end date is set
to a value determined by the -days option. Any certificate
extensions are retained unless the -clrext option is supplied. If
the input is a certificate request, then a self-signed certificate
is created using the supplied private key using the subject name in
the request.
-clrext Deletes any extensions from a certificate. This option is used when
a certificate is being created from another certificate, such as
with the -signkey or the -CA options. Normally all extensions are
retained.
-keyform PEM|DER
Specifies the format (DER or PEM) of the private key file used in
the -signkey option.
-days arg
Specifies the number of days to make a certificate valid. The
default is 30 days.
-x509toreq
Converts a certificate into a certificate request. The -signkey
option is used to pass the required private key.
-req By default a certificate is expected on input. With this option, a
certificate request is expected instead.
-CA filename
Specifies the CA certificate to be used for signing. When this
option is present x509 behaves like a mini CA. The input file is
signed by this CA using this option, meaning its issuer name is set
to the subject name of the CA and it is digitally signed using the
CA's private key.
This option is normally combined with the -req option. Without the
-req option the input is a certificate which must be self-signed.
-CAkey filename
Sets the CA private key to sign a certificate with. If this option
is not specified then it is assumed that the CA private key is
present in the CA certificate file.
-CAserial filename
Sets the CA serial number file to use.
When the -CA option is used to sign a certificate it uses a serial
number specified in a file. This file consist of one line
containing an even number of hex digits with the serial number to
use. After each use the serial number is incremented and written
out to the file again.
The default filename consists of the CA certificate file base name
with .srl appended. For example, if the CA certificate file is
called mycacert.pem it expects to find a serial number file called
mycacert.srl.
-CAcreateserial filename
Creates a CA serial number file if it does not exist. It will
contain the serial number 02 and the certificate being signed will
have the number 1 as its serial number. Normally, if the -CA option
is specified and the serial number file does not exist it is an
error.
-extfile filename
File containing certificate extensions to use. If not specified
then no extensions are added to the certificate.
-extensions section
The section to add certificate extensions from. If this option is
not specified then the extensions should either be contained in the
unnamed (default) section or the default section should contain a
variable called extensions which contains the section to use.
NAME OPTIONS
The nameopt command line option determines how the subject and issuer names
are displayed. If no nameopt option is present the default oneline format
is used which is compatible with previous versions of OpenSSL. Each option
is described in detail below. All options can be preceded by a - to turn
the option off. Usually, only the first four are used.
compat Uses the old format. This is equivalent to specifying no name
options.
RFC2253 Displays names compatible with RFC2253 equivalent to esc_2253,
esc_ctrl, esc_msb, utf8, dump_nostr, dump_unknown, dump_der,
sep_comma_plus, dn_rev and sname.
oneline A oneline format which is more readable than RFC2253. It is
equivalent to esc_2253, esc_ctrl, esc_msb, utf8, dump_nostr,
dump_der, use_quote, sep_comma_plus_spc, spc_eq and sname options.
multiline
A multiline format. It is equivalent to esc_ctrl, esc_msb,
sep_multiline, spc_eq and lname.
esc_2253
Escapes the special characters required by RFC2253 in a field.
These characters are ,+"<>;. Additionally # is escaped at the
begining of a string and a space character at the beginning or end
of a string.
esc_ctrl
Escapes control characters. These characters are those with ASCII
values less than 0x20 (space) and the delete (0x7f) character. They
are escaped using the RFC2253 \XX notation, where XX are two hex
digits representing the character value.
esc_msb Escapes characters with the MSB set, that is with ASCII values
larger than 127.
use_quote
Escapes some characters by surrounding the whole string with "
characters. Without the option, all escaping is done with the \
character.
utf8 Converts all strings to UTF8 format first. This is required by
RFC2253. If you have a UTF8 compatible terminal then the use of
this option (and not setting esc_msb) may result in the correct
display of multibyte (international) characters. Is this option is
not present, then multibyte characters larger than 0xff will be
represented using the format \UXXXX for 16 bits and \WXXXXXXXX for
32 bits. Also, if this option is off any UTF8Strings will be
converted to their character form first.
no_type Does not attempt to interpret multibyte characters in any way.
Their content octets are merely dumped as though one octet
represents each character. This is useful for diagnostic purposes
but will result in rather odd looking output.
show_type
Shows the type of the ASN1 character string. The type precedes the
field contents. For example, BMPSTRING: Hello World.
dump_der
When this option is set any fields that need to be hexdumped will
be dumped using the DER encoding of the field. Otherwise, just the
content octets will be displayed. Both options use the RFC2253
#XXXX... format.
dump_nostr
Dumps non-character string types, such as OCTET STRING. If this
option is not set then non-character string types will be displayed
as though each content octet repesents a single character.
dump_all
Dumps all fields. This option when used with dump_der allows the
DER encoding of the structure to be unambiguously determined.
dump_unknown
Dumps any field whose OID is not recognized by OpenSSL.
sep_comma_plus, sep_comma_plus_space, sep_semi_plus_space,sep_multiline
Determines the field separators. The first character is between
RDNs and the second between multiple AVAs. (Multiple AVAs are very
rare and their use is discouraged.) The options ending in space
additionally place a space after the separator to make it more
readable. The sep_multiline uses a linefeed character for the RDN
separator and a spaced + for the AVA separator. It also indents the
fields by four characters.
dn_rev Reverses the fields of the DN. This is required by RFC2253. As a
side effect this also reverses the order of multiple AVAs, but this
is permissible.
nofname, sname, lname, oid
Alter how the field name is displayed. The nofname option does not
display the field at all. The sname option uses the short name form
(CN for commonName, for example), and the lname option uses the
long form. The oid option represents the OID in numerical form and
is useful for diagnostic purpose.
spc_eq Places spaces around the = character which follows the field name.
DESCRIPTION
The x509 command is a multipurpose certificate utility. It can be used to
display certificate information, convert certificates to various forms,
sign certificate requests such as a mini CA, or edit certificate trust
settings. Since there are a large number of options they are divided into
various sections.
NOTES
The PEM format uses the following header and footer lines:
-----BEGIN CERTIFICATE----
-----END CERTIFICATE----
It will also handle files containing:
-----BEGIN X509 CERTIFICATE----
-----END X509 CERTIFICATE----
Trusted certificates have the following lines:
-----BEGIN TRUSTED CERTIFICATE----
-----END TRUSTED CERTIFICATE----
The conversion to UTF8 format used with the name options assumes that
T61Strings use the ISO8859-1 character set. This is wrong, but Netscape and
MSIE do this, as do many certificates. So, although this is incorrect, it
is more likely to display the majority of certificates correctly.
The -fingerprint option takes the digest of the DER encoded certificate.
This is commonly called a fingerprint. Because of the nature of message
digests, the fingerprint of a certificate is unique to that certificate.
Two certificates with the same fingerprint can be considered to be the
same.
The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
The -email option searches the subject name and the subject alternative
name extension. Only unique email addresses will be printed out. It will
not print the same address more than once.
RESTRICTIONS
Extensions in certificates are not transferred to certificate requests and
vice versa.
It is possible to produce invalid certificates or requests by specifying
the wrong private key or using inconsistent options in some cases. These
should be checked.
There should be options to explicitly set such things as start and end
dates rather than an offset from the current time.
The code to implement the verify behavior described in the Trust Settings
is under development. It describes the intended behavior rather than the
current behavior.
EXAMPLES
In these examples the \ character means the example should be on one line.
Display the contents of a certificate:
openssl x509 -in cert.pem -noout -text
Display the certificate serial number:
openssl x509 -in cert.pem -noout -serial
Display the certificate subject name:
openssl x509 -in cert.pem -noout -subject
Display the certificate subject name in RFC2253 form:
openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
Display the certificate subject name in oneline form on a terminal
supporting UTF8:
openssl x509 -in cert.pem -noout -subject -nameopt oneline -nameopt -escmsb
Display the certificate MD5 fingerprint:
openssl x509 -in cert.pem -noout -fingerprint
Display the certificate SHA1 fingerprint:
openssl x509 -sha1 -in cert.pem -noout -fingerprint
Convert a certificate from PEM to DER format:
openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
Convert a certificate to a certificate request:
openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
Convert a certificate request into a self signed certificate using
extensions for a CA:
openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
-signkey key.pem -out cacert.pem
Sign a certificate request using the CA certificate above and add user
certificate extensions:
openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
-CA cacert.pem -CAkey key.pem -CAcreateserial
Set a certificate to be trusted for SSL client use and change set its alias
to "Steve's Class 1 CA"
openssl x509 -in cert.pem -addtrust sslclient \
-alias "Steve's Class 1 CA" -out trust.pem
SEE ALSO
Commands: req(1ssl), ca(1ssl), genrsa(1ssl), gendsa(1ssl), verify(1ssl)
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